The present invention relates to unclonable functions, and more specifically, to physical unclonable functions.
A physical unclonable function (PUF) is a function that is arranged in a physical structure that is typically easily evaluated, but difficult to predict. A PUF device should be very difficult to duplicate, but relatively simple to fabricate.
A PUF generates a set of bits, for example, 128 bits to form a matrix A. During operation the calculation Y=A*X is performed, where A is a matrix having elements generated from the PUF, X is an input vector called a “challenge,” and Y is the output vector called the “response.”
The matrix A and the input vector should only be known to the chip owner such that only the owner may know if the response is correct.
Typical PUF characteristics include stable bit generation from the PUF that remain fixed over time, and correlation among the bits generated from similar PUF structures should be random.